The present invention is an improvement of U.S. patent applications (hereinafter defined as "prior arts") also filed by the same inventor of this application, including U.S. Ser. No.: 09/320,857, filed on: May 26, 1999 and U.S. Ser. No.: 09/329,175, filed on: Jun. 9, 1999, etc.
The prior arts disclosed an outer-rotor type electric motor, as shown in FIG. 16 as accompanied in this application, including: an inner stator 1 fixed on a stator holder 2, and an outer rotor 3 rotatably circumferentially disposed about the inner stator 1 about an axis X. The outer rotor 3 includes: a cylinder member 31 and a magnetic conductor 30 secured to an inside wall of the cylinder member 31, having an interface I cylindrically defined between the magnetic conductor 30 and the cylinder member 31 without intermeshing the conductor 30 and the cylinder member 31. Such a smooth interface I may cause loosening or separation of the magnetic conductor 30 from the cylinder member 31, thereby easily damaging or deteriorating the electric motor.
The present inventor has found the drawbacks of the prior arts and invented the present anti-loosening outer rotor device for an outerrotor type electric motor with high torque output.